There are several kinds of carbon graphite for mechanical seal, which are different in nature. Must be familiar with various carbon grades, properties and sources of supply. The following are some of the failure modes and how to choose such materials.

1 high wear, at present, in the mechanical seal material exists a tendency that no matter what the conditions are using hard carbon graphite, that the higher the hardness wear resistance. In some cases, however, this is not the case. For example, the lubricity of medium or poor, no lubrication, or easy to produce dry friction situations, such as light hydrocarbon medium, the use of hard M106K wear large, high pure electrographite soft wear small, this is because of the low friction soft graphite has excellent performance. It is composed of graphite crystal, good self-lubricating performance, there is a very thin layer of graphite film to transfer dual surface during operation, the friction surface lubrication, the friction coefficient decreased, reducing wear.

When the team material is sprayed ceramic, with medium hardness of graphite is appropriate. If the content of solid particles in the medium carbon graphite is more than 5%, not as a single seal material team, also should not be used as the main sealing ring arranged in series. Otherwise, the seal will wear high.

2 blister in Changzhou, high temperature heat pump, often find carbon ring Changzhou Wujin hot oil pump mechanical seal on the pits, scar blocks. This is the choice of carbon graphite materials, the study did not fully study the combination of impregnated with carbon graphite materials. The temperature range of the carbon graphite seal is different with the impregnation. For example, phenol aldehyde resin graphite, when the temperature exceeds 180 degrees Celsius, the resin will decompose to form hard grains and precipitation of volatiles, scar formation, thus greatly increase the friction, the surface damage degree, to reduce the frictional heat caused by the temperature rise is effective. Therefore, the appropriate reduction of carbon graphite ring friction width is conducive to prevent the occurrence of bubble scar. Poor quality carbon graphite ring, because of the internal pores more, the use of gas expansion, the carbon particles and resin volatiles blown out to form a bubble scar. Sealing of the end face will be stopped when the adhesion. Therefore, the leaching of copper or antimony impregnated graphite.